Benzenediazonium chloride

Benzenediazonium chloride


IUPAC name Benzenediazonium chloride
Other names Phenyldiazonium chloride
Identifiers
CAS number	100-34-5^Y
PubChem	60992
ChemSpider	54953^Y
Jmol-3D images	Image 1
SMILES [Cl-].N#[N+]c1ccccc1
InChI InChI=1S/C6H5N2.ClH/c7-8-6-4-2-1-3-5-6;/h1-5H;1H/q+1;/p-1^Y Key: CLRSZXHOSMKUIB-UHFFFAOYSA-M^Y InChI=1/C6H5N2.ClH/c7-8-6-4-2-1-3-5-6;/h1-5H;1H/q+1;/p-1 Key: CLRSZXHOSMKUIB-REWHXWOFAT
Properties
Molecular formula	C₆H₅ClN₂
Molar mass	140.57 g mol⁻¹
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Benzenediazonium chloride is the diazonium compound of aniline. It is used in the preparation of azo compounds (e.g. azo dyes). It is synthesised from nitrous acid and aniline. Nitrous acid is prepared in situ because it is not stable enough to be stored.

Synthesis

This compound is easily prepared by ordinary methods of diazotization: by dissolving aniline in ice-cold hydrochloric acid, followed by addition of sodium nitrite.^[1] The reactions which occur are:

Preparation of nitrous acid:

NaNO₂ + HCl → HNO₂ + NaCl

The nitrous acid formed is reacted with aniline to give benzenediazonium chloride:

C₆H₅NH₂ + HNO₂ + HCl → [C₆H₅N⁺≡N][Cl⁻]

The temperature must be kept between 0-5 °C to avoid the product from decomposing to give dinitrogen. Due to its instability, this compound is not commercially available. Workers have mentioned the violent decomposition of this compound, even without any heat or strong light near the bottle.^[2]

Diazo coupling reactions

Benzenediazonium chloride can react with phenol or aniline, via diazo coupling reactions, to give azo compounds:

References

^ J. B. Conant, R. E. Lutz, B. B. Corson (1941), "1,4-Aminonaphthol hydrochloride", Org. Synth. ; Coll. Vol. 1: 49
^ A. N. Nesmajanow (1943), "β-Naphthylmercuric chloride", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv2p0432 ; Coll. Vol. 2: 432